Azithromycin Protects against Zika Virus Infection by Upregulating Virus-Induced Type I and III Interferon Responses

Azithromycin (AZM) is a widely used antibiotic, with additional antiviral and anti-inflammatory properties that remain poorly understood. Although Zika virus (ZIKV) poses a significant threat to global health, there are currently no vaccines or effective therapeutics against it. Here, we report that AZM effectively suppresses ZIKV infection in vitro by targeting a late stage in the viral life cycle. In addition, AZM upregulates the expression of host type I and III interferons and several of their downstream interferon-stimulated genes in response to ZIKV infection. In particular, we found that AZM upregulated the expression of MDA5 and RIG-I (pathogen recognition receptors induced by ZIKV infection) and increased the levels of phosphorylated TBK1 and IRF3. Interestingly, AZM treatment upregulated the phosphorylation of TBK1 without inducing the phosphorylation of IRF3 by itself. These findings highlight the potential use of AZM as a broad antiviral agent to combat viral infection and to prevent devastating ZIKV-associated clinical outcomes, such as congenital microcephaly.